Glossary

This section is informative.

A wide variety of terms are used in the realm of digital identity. While many definitions are consistent with earlier versions of SP 800-63, some have changed in this revision. Many of these terms lack a single, consistent definition, warranting careful attention to how the terms are defined here.

applicant

A subject undergoing the processes of identity proofing and enrollment.

applicant reference

A representative of the applicant who can vouch for the identity of the applicant, specific attributes related to the applicant, or conditions relative to the context of the individual (e.g., emergency status, homelessness).

approved cryptography

An encryption algorithm, hash function, random bit generator, or similar technique that is Federal Information Processing Standard (FIPS)-approved or NIST-recommended. Approved algorithms and techniques are either specified or adopted in a FIPS or NIST recommendation.

assertion

A statement from an IdP to an RP that contains information about an authentication event for a subscriber. Assertions can also contain identity attributes for the subscriber.

attribute

A quality or characteristic ascribed to someone or something. An identity attribute is an attribute about the identity of a subscriber.

attribute validation

The process or act of confirming that a set of attributes are accurate and associated with a real-life identity. See validation.

authenticate

See authentication.

authentication

The process by which a claimant proves possession and control of one or more authenticators bound to a subscriber account to demonstrate that they are the subscriber associated with that account.

Authentication Assurance Level (AAL)

A category that describes the strength of the authentication process.

authenticator

Something that the subscriber possesses and controls (e.g., a cryptographic module or password) and that is used to authenticate a claimant’s identity. See authenticator type and multi-factor authenticator.

authenticity

The property that data originated from its purported source.

authoritative source

An entity that has access to or verified copies of accurate information from an issuing source such that a CSP has high confidence that the source can confirm the validity of the identity attributes or evidence supplied by an applicant during identity proofing. An issuing source may also be an authoritative source. Often, authoritative sources are determined by a policy decision of the agency or CSP before they can be used in the identity proofing validation phase.

authorize

A decision to grant access, typically automated by evaluating a subject’s attributes.

biometric reference

One or more stored biometric samples, templates, or models attributed to an individual and used as the object of biometric comparison in a database, such as a facial image stored digitally on a passport, fingerprint minutiae template on a National ID card or Gaussian Mixture Model for speaker recognition.

biometric sample

An analog or digital representation of biometric characteristics prior to biometric feature extraction, such as a record that contains a fingerprint image.

biometrics

Automated recognition of individuals based on their biological or behavioral characteristics. Biological characteristics include but are not limited to fingerprints, palm prints, facial features, iris and retina patterns, voiceprints, and vein patterns. Behavioral characteristics include but are not limited to keystrokes, angle of holding a smart phone, screen pressure, typing speed, mouse or mobile phone movements, and gyroscope position.

claimant

A subject whose identity is to be verified using one or more authentication protocols.

claimed address

The physical location asserted by a subject where they can be reached. It includes the individual’s residential street address and may also include their mailing address.

claimed identity

An applicant’s declaration of unvalidated and unverified personal attributes.

core attributes

The set of identity attributes that the CSP has determined and documented to be required for identity proofing.

credential service provider (CSP)

A trusted entity whose functions include identity proofing applicants to the identity service and registering authenticators to subscriber accounts. A CSP may be an independent third party.

credible source

An entity that can provide or validate the accuracy of identity evidence and attribute information. A credible source has access to attribute information that was validated through an identity proofing process or that can be traced to an authoritative source, or it maintains identity attribute information obtained from multiple sources that is checked for data correlation for accuracy, consistency, and currency.

digital identity

An attribute or set of attributes that uniquely describes a subject within a given context.

digital signature

An asymmetric key operation in which the private key is used to digitally sign data and the public key is used to verify the signature. Digital signatures provide authenticity protection, integrity protection, and non-repudiation support but not confidentiality or replay attack protection.

disassociability

Enabling the processing of PII or events without association to individuals or devices beyond the operational requirements of the system. [NISTIR8062]

electronic authentication (e-authentication)

See digital authentication.

enrollment

The process through which a CSP/IdP provides a successfully identity-proofed applicant with a subscriber account and binds authenticators to grant persistent access.

entropy

The amount of uncertainty that an attacker faces to determine the value of a secret. Entropy is usually stated in bits. A value with n bits of entropy has the same degree of uncertainty as a uniformly distributed n-bit random value.

equity

The consistent and systematic fair, just, and impartial treatment of all individuals, including individuals who belong to underserved communities that have been denied such treatment, such as Black, Latino, and Indigenous and Native American persons, Asian Americans and Pacific Islanders, and other persons of color; members of religious minorities; lesbian, gay, bisexual, transgender, and queer (LGBTQ+) persons; persons with disabilities; persons who live in rural areas; and persons otherwise adversely affected by persistent poverty or inequality. [EO13985]

Federal Information Processing Standard (FIPS)

Under the Information Technology Management Reform Act (Public Law 104-106), the Secretary of Commerce approves the standards and guidelines that the National Institute of Standards and Technology (NIST) develops for federal computer systems. NIST issues these standards and guidelines as Federal Information Processing Standards (FIPS) for government-wide use. NIST develops FIPS when there are compelling federal government requirements, such as for security and interoperability, and there are no acceptable industry standards or solutions. See background information for more details.

FIPS documents are available online on the FIPS home page: https://www.nist.gov/itl/fips.cfm

federation

A process that allows for the conveyance of identity and authentication information across a set of networked systems.

Federation Assurance Level (FAL)

A category that describes the process used in a federation transaction to communicate authentication events and subscriber attributes to an RP.

hash function

A function that maps a bit string of arbitrary length to a fixed-length bit string. Approved hash functions satisfy the following properties:

One-way — It is computationally infeasible to find any input that maps to any pre-specified output.
Collision-resistant — It is computationally infeasible to find any two distinct inputs that map to the same output.

identifier

A data object that is associated with a single, unique entity (e.g., individual, device, or session) within a given context and is never assigned to any other entity within that context.

identity

See digital identity

Identity Assurance Level (IAL)

A category that conveys the degree of confidence that the subject’s claimed identity is their real identity.

identity evidence

Information or documentation that supports the real-world existence of the claimed identity. Identity evidence may be physical (e.g., a driver’s license) or digital (e.g., a mobile driver’s license or digital assertion). Evidence must support both validation (i.e., confirming authenticity and accuracy) and verification (i.e., confirming that the applicant is the true owner of the evidence).

identity proofing

The processes used to collect, validate, and verify information about a subject in order to establish assurance in the subject’s claimed identity.

identity provider (IdP)

The party in a federation transaction that creates an assertion for the subscriber and transmits the assertion to the RP.

identity resolution

The process of collecting information about an applicant to uniquely distinguish an individual within the context of the population that the CSP serves.

identity verification

See verification

injection attack

An attack in which an attacker supplies untrusted input to a program. In the context of federation, the attacker presents an untrusted assertion or assertion reference to the RP in order to create an authenticated session with the RP.

issuing source

An authority responsible for the generation of data, digital evidence (i.e., assertions), or physical documents that can be used as identity evidence.

knowledge-based verification (KBV)

A process of validating knowledge of personal or private information associated with an individual for the purpose of verifying the claimed identity of an applicant. KBV does not include collecting personal attributes for the purposes of identity resolution.

legal person

An individual, organization, or company with legal rights.

manageability

Providing the capability for the granular administration of personally identifiable information, including alteration, deletion, and selective disclosure. [NISTIR8062]

natural person

A real-life human being, not synthetic or artificial.

network

An open communications medium, typically the Internet, used to transport messages between the claimant and other parties. Unless otherwise stated, no assumptions are made about the network’s security; it is assumed to be open and subject to active (e.g., impersonation, session hijacking) and passive (e.g., eavesdropping) attacks at any point between the parties (e.g., claimant, verifier, CSP, RP).

non-repudiation

The capability to protect against an individual falsely denying having performed a particular transaction.

offline attack

An attack in which the attacker obtains some data (typically by eavesdropping on an authentication transaction or by penetrating a system and stealing security files) that the attacker is able to analyze in a system of their own choosing.

one-to-one (1:1) comparison

The process in which a biometric sample from an individual is compared to a biometric reference to produce a comparison score.

online attack

An attack against an authentication protocol in which the attacker either assumes the role of a claimant with a genuine verifier or actively alters the authentication channel.

online service

A service that is accessed remotely via a network, typically the internet.

personal information

See personally identifiable information.

personally identifiable information (PII)

Information that can be used to distinguish or trace an individual’s identity, either alone or when combined with other information that is linked or linkable to a specific individual. [A-130]

personally identifiable information processing

An operation or set of operations performed upon personally identifiable information that can include the collection, retention, logging, generation, transformation, use, disclosure, transfer, or disposal of personally identifiable information.

practice statement

A formal statement of the practices followed by the parties to an authentication process (e.g., CSP or verifier). It usually describes the parties’ policies and practices and can become legally binding.

predictability

Enabling reliable assumptions by individuals, owners, and operators about PII and its processing by an information system. [NISTIR8062]

private key

In asymmetric key cryptography, the private key (i.e., a secret key) is a mathematical key used to create digital signatures and, depending on the algorithm, decrypt messages or files that are encrypted with the corresponding public key. In symmetric key cryptography, the same private key is used for both encryption and decryption.

processing

Operation or set of operations performed upon PII that can include, but is not limited to, the collection, retention, logging, generation, transformation, use, disclosure, transfer, and disposal of PII. [NISTIR8062]

presentation attack

Presentation to the biometric data capture subsystem with the goal of interfering with the operation of the biometric system.

presentation attack detection (PAD)

Automated determination of a presentation attack. A subset of presentation attack determination methods, referred to as liveness detection, involves the measurement and analysis of anatomical characteristics or voluntary or involuntary reactions, to determine if a biometric sample is being captured from a living subject that is present at the point of capture.

process assistant

An individual who provides support for the proofing process but does not support decision-making or risk-based evaluation (e.g., translation, transcription, or accessibility support).

proofing agent

An agent of the CSP who is trained to attend identity proofing sessions and can make limited risk-based decisions – such as physically inspecting identity evidence and making physical comparisons of the applicant to identity evidence.

Privacy Impact Assessment (PIA)

A method of analyzing how personally identifiable information (PII) is collected, used, shared, and maintained. PIAs are used to identify and mitigate privacy risks throughout the development lifecycle of a program or system. They also help ensure that handling information conforms to legal, regulatory, and policy requirements regarding privacy.

pseudonym

A name other than a legal name.

pseudonymity

The use of a pseudonym to identify a subject.

pseudonymous identifier

A meaningless but unique identifier that does not allow the RP to infer anything regarding the subscriber but that does permit the RP to associate multiple interactions with a single subscriber.

public key

The public part of an asymmetric key pair that is used to verify signatures or encrypt data.

public key certificate

A digital document issued and digitally signed by the private key of a certificate authority that binds an identifier to a subscriber’s public key. The certificate indicates that the subscriber identified in the certificate has sole control of and access to the private key. See also [RFC5280].

public key infrastructure (PKI)

A set of policies, processes, server platforms, software, and workstations used to administer certificates and public-_private key_ pairs, including the ability to issue, maintain, and revoke public key certificates.

registration

See enrollment.

relying party (RP)

An entity that relies upon a verifier’s assertion of a subscriber’s identity, typically to process a transaction or grant access to information or a system.

remote

A process or transaction that is conducted through connected devices over a network, rather than in person.

resolution

See identity resolution.

risk assessment

The process of identifying, estimating, and prioritizing risks to organizational operations (i.e., mission, functions, image, or reputation), organizational assets, individuals, and other organizations that result from the operation of a system. A risk assessment is part of risk management, incorporates threat and vulnerability analyses, and considers mitigations provided by security controls that are planned or in-place. It is synonymous with “risk analysis.”

risk management

The program and supporting processes that manage information security risk to organizational operations (including mission, functions, image, reputation), organizational assets, individuals, and other organizations and includes (i) establishing the context for risk-related activities, (ii) assessing risk, (iii) responding to risk once determined, and (iv) monitoring risk over time.

RP subscriber account

An account established and managed by the RP in a federated system based on the RP’s view of the subscriber account from the IdP. An RP subscriber account is associated with one or more federated identifiers and allows the subscriber to access the account through a federation transaction with the IdP.

Senior Agency Official for Privacy (SAOP)

Person responsible for ensuring that an agency complies with privacy requirements and manages privacy risks. The SAOP is also responsible for ensuring that the agency considers the privacy impacts of all agency actions and policies that involve PII.

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social engineering: The act of deceiving an individual into revealing sensitive information, obtaining unauthorized access, or committing fraud by associating with the individual to gain confidence and trust.
subject: A person, organization, device, hardware, network, software, or service. In these guidelines, a subject is a natural person.
subscriber: An individual enrolled in the CSP identity service.
subscriber account: An account established by the CSP containing information and authenticators registered for each subscriber enrolled in the CSP identity service.
supplemental controls: Controls that may be added, in addition to those specified in the organization’s tailored assurance level, in order to address specific threats or attacks.
synthetic identity fraud: The use of a combination of personally identifiable information (PII) to fabricate a person or entity in order to commit a dishonest act for personal or financial gain.
system of record (SOR): An SOR is a collection of records that contain information about individuals and are under the control of an agency. The records can be retrieved by the individual’s name or by an identifying number, symbol, or other identifier.
System of Record Notice (SORN): A notice that federal agencies publish in the Federal Register to describe their systems of records.
transaction: See digital transaction
trust agreement: A set of conditions under which a CSP, IdP, and RP are allowed to participate in a federation transaction for the purposes of establishing an authentication session between the subscriber and the RP.
trusted referee: An agent of the CSP who is trained to make risk-based decisions regarding an applicant’s identity proofing case when that applicant is unable to meet the expected requirements of a defined IAL proofing process.
usability: The extent to which a product can be used by specified users to achieve specified goals with effectiveness, efficiency, and satisfaction in a specified context of use. [ISO/IEC9241-11]
validation: The process or act of checking and confirming that the evidence and attributes supplied by an applicant are authentic, accurate and associated with a real-life identity. Specifically, evidence validation is the process or act of checking that the presented evidence is authentic, current, and issued from an acceptable source. See also attribute validation.
verification: The process or act of confirming that the applicant undergoing identity proofing holds the claimed real-life identity represented by the validated identity attributes and associated evidence. Synonymous with “identity verification.”
verifier: An entity that verifies the claimant’s identity by verifying the claimant’s possession and control of one or more authenticators using an authentication protocol. To do this, the verifier needs to confirm the binding of the authenticators with the subscriber account and check that the subscriber account is